code: def test_is_variable(self):
      self.assertTrue(tensor_util.is_variable(tf.Variable(0.0)))
      self.assertTrue(
          tensor_util.is_variable(tf.Variable(0.0, trainable=False))
      )
  
imports: import numpy
  import tensorflow.compat.v2
  from tensorflow_probability.python.bijectors import scale
  from tensorflow_probability.python.distributions import normal
  from tensorflow_probability.python.internal import tensor_util
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.util import deferred_tensor
label_desc: Use image node_id 3 for calling the VariableTrackingUtils obj's underlying member method code with example usage: obj.test_is_variable() without return types